The purpose of this application is to obtain support for one additional full-time medical genealogist who will be attached to the staff of the Genetics Registry of the Medical Research Council's Human Genetics Unit, Edinburgh, Scotland. The specific remit of that individual will be to extend and verify the details of family histories obtained by the principal investigator and the two co-investigators from patients attending "cancer family" clinics in Edinburgh, Glasgow, Aberdeen and Dundee. These clinics provide a comprehensive counselling and investigation service for patients with a family history of cancer (notably for women at increased risk of breast/ovarian cancer on the basis of family history). Their operation is co-ordinated and, in the setting of a uniform health service, they offer the prospect of near-complete coverage of the Scottish population. The distinctive Scottish records of Births, Marriages and Deaths, to which the MRC registry has privileged access, facilitate the construction of very large and accurate pedigrees which, in turn, are the starting point for precise estimation of risks to individual family members, for establishment of an at-risk register, for mapping of cancer genes by linkage analysis, for epidemiological studies on the interaction of genetic and environmental factors in carcinogenesis and for intervention trials in high-risk groups. These longer-term objectives lie beyond the scope of the present application but are clearly dependent upon the efficiency with which extended family trees can be constructed. Because of rapidly increasing demand for the services of "cancer family" clinics, the present resources of the MRC Genetics Registry are severely strained. An additional full-time genealogist to search the Registrar General's records to trace ancestors and collateral branches of families of patients attending these clinics will accelerate a crucial rate-limiting step for much important research.